Number : A number $x$ is a mathematical symbol representing a quantity.

Subtraction : Subtraction is the mathematical operation that describes decreasing a number by an amount equal to a second number. The mathematical symbol for subtraction is the minus sign $-.$ The term subtraction is also used for a generalization of this basic operation on numbers to functions, vectors and matrices.

Multiplication : Multiplication is the mathematical operation that is a shorthand for adding the same amount several times. For example $3\cdot 4=4+4+4=12.$

Standard algorithm : By standard algorithm we refer to any one of the algorithms that are commonly taught at school to add, subtract, multiply or divide multi-digit numbers such as long division and partial products multiplication.

Line : A line AB is a one-dimensional shape that includes the points A and B, all the points on the line segment in between A and B and all the points of the straight extension of the line segment beyond A and B. A line does not have an endpoint.

Linear : Linear means in a way that can be described by a combination of addition and scalar multiplication. See also linear function, linear equation and linear combination.

Negative : A number is negative if it is $\lt 0.$

Positive : Positive means $\geq 0.$

Scatter plot : A way to visualize the dependency realtionship between two variables. Every common outcome of the two variables is plotted as a point in the coordinate system by having the x-coordinate of the point equal to the outcome of the first variable and the y-coordinate of the point equal to the outcome of the second variable.

Variable : A letter in an expression or function that represents an arbitrary number.